<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<base href="a.html" target="_blank" />
<!--
//网页中所有超链接标签的默认指向窗口和打开方式；
-->
</head>
<body>
	<script type="text/javascript">
		var str = "Hello world!你好"
		document.write(str);
		document.write(str.sub(3))
		document.write(str.sup(3))
		document.write(str.valueOf())
		document.write(str.fixed())
	</script>

</body>
</html>